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<head>
    <meta charset="UTF-8">
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    <title>Document</title>
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<body>
    <script>
        var emailReg = /^\w{3,}(\.\w+)*@[A-z0-9]+(\.[A-z]{2,5}){1,2}$/;
        var reg = /^\w+@[A-z0-9]+(.[A-z]{2,5}){1,2}/;

        var email = "haha.hello@163.com";

        console.log(reg.test(email));
    </script>
</body>

</html>